Performing an effective trunk twist requires targeting the core muscles. When performing trunk exercises an exerciser must use a machine or device to stabilize the upper body to avoid using the muscles of the scapula and glenohumeral joint. By avoiding the use of these shoulder muscles an exerciser maximizes the use of the core muscles of the trunk, thus strengthening those core muscles in the most effective manner. Until now, the only exercise machines that could maximize the use of core muscles were extremely bulky and expensive. For those reasons, the previous art was typically suitable for only large commercial gyms.
Traditionally, trunk twist exercises have been performed either (1) on a seated torso rotation machine, which stabilizes both the upper and lower body, such as the technology disclosed by U.S. Pat. No. 4,456,245 (“the '245 patent”), or (2) standing, with arms extended holding a cable or a resistance band, such as the technology disclosed by U.S. Pat. No. 7,625,321 (“the '321 patent”).
The seated torso rotation machine is effective by providing a guided path of motion, parallel to the resistance, and the trunk muscles are driving the majority of the force necessary to complete the exercise. In this exercise, sitting down stabilizes the lower body, the shoulder pads stabilize the shoulder complex, and thus the upper body alone drives the force of motion. Accordingly, the trunk muscles are sufficiently isolated, requiring the trunk muscles to perform a majority of the work. However, the machine is too expensive and too bulky for many commercial gyms, and virtually all home gyms.
Because a seated torso rotation machine is often unavailable, many exercisers perform a trunk twist exercise standing, with arms extended, holding a cable or a resistance band, and twisting in each direction. With the standing exercise, because the exerciser is holding the cable at arm's length in front of the chest, the shoulder complex influences the effectiveness of the exercise. In this exercise, where the load is distal to the body, this lack of stability and restraint in the upper body greatly reduces the amount of force through the trunk. But, because the arms and shoulders are still working to perform the twist, and exerciser often does not realize that the arms and shoulders are helping to perform the exercise, reducing the amount of force through the trunk. In an effort to alleviate this problem, users can perform this exercise holding a large exercise ball in between the arms. The addition of the exercise ball greatly increases the stability through the shoulder complex, making the exercise more efficient, but holding the ball between the arms is virtually impossible because the ball is bulky and uncomfortable to hold.
The Ground Force 360, which is explained at http://rotationalexercise.com/ground-force-360/, is similar to the seated torso rotation machine, as disclosed in the '245 patent, because it effectively loads the trunk muscles and provides a guided path of resistance that is parallel to the path of motion. In this exercise, the user stands at the machine and has shoulder-stabilizing pads on the front and back of each shoulder. Similar to the shoulder pads in the '245 patent, the shoulder pads on the Ground Force 360 stabilize the shoulder complex, allowing the user to drive the maximum amount of force through the trunk muscles. However, the Ground Force 360, similar to the seated torso rotation machine, is too expensive and too bulky for most commercial gyms, and virtually all home gyms.
Trunk twists may also be performed by adding weight to an exerciser's shoulders at the back of the neck using a weighted bar, such as the technology disclosed by U.S. Pat. No. 5,312,314 (“the '314 patent), or similarly with a semicircular bar as disclosed in U.S. Pat. No. 5,248,287 (“the '287 patent”). These exercises, however, load the trunk muscles inefficiently. Exercise is most effective when loads and the direction of resistance are parallel. The load and resistance in this exercise is perpendicular to the path of motion. Accordingly, this exercise is not an effective way to load the trunk muscles for a twisting exercise.
Another method of adding resistance is by using air resistance with a paddle on the shoulders that would provide air resistance during a twisting motion, such as the technology disclosed in U.S. Pat. No. 4,603,854 (“the '854 patent”). Because of the air paddles, the load and the direction of resistance are parallel. However, the speed of motion, which dictates the amount of force, requires an exerciser to move faster in order to increase resistance. The faster motion leads to a greater risk of injury. Accordingly, using air resistance with a paddle on the shoulders, because it does not allow the user to increase the resistance while maintaining a constant speed, is not the most effective way to perform this exercise.
Despite existing resistance based exercise machines, there still exists problems with the existing machines that stabilize the upper body, removing the scapular/glenohumeral involvement in a trunk twist, because these machines are bulky, not portable, and expensive. There also still exists problems with other machines and methods that are more portable and/or less expensive, because those machines and methods fail to stabilize the upper body, thus allowing scapular/glenohumeral involvement in a trunk twist exercise, and thus greatly reducing the amount of force production through the trunk and core muscles. In most of these methods and exercises, the load is also not the most efficient for the exercise: it is either distal to the body, or it is not parallel to the direction of resistance.
Despite existing resistance based exercise machines, there still exists a need for a resistance based trunk rotation device which is portable, lightweight, less bulky, less expensive, stabilizes the upper body, removing scapular/glenohumeral involvement in the exercise, and thus increasing the efficiency of the exercise and the ability of the exercise to exert force production through the trunk and core muscles, and can be loaded progressively over time as the exerciser gets stronger.
One embodiment of the exercise device is illustrated in FIG. 1A (top view), FIG. 1B (front view), and FIG. 10 (side view).
At each end of the quarter-wheel is a means for attaching resistance, 18. One example of the means for attaching resistance is a bar inlaid in a hole in the quarter-wheel (FIG. 1B). Other examples of means for attaching resistance include a ring, a hook, a spring clip, a hole inlaid in the quarter-wheel, a claw similar in shape and rigidity to a nail puller, to hold the resistance in place (FIG. 3B), or a combination of any of the various means for attaching resistance. The means for attaching resistance can be placed in a variety of locations on the disclosed devices, including on only one side of the quarter-wheel, at a corner of the quarter-wheel and parallel to the support means, or at any point on the outside or inside of the quarter-wheel. In one embodiment, the means for attaching resistance is the same plastic as the quarter-wheel. In one embodiment, the means for attaching resistance are another type of plastic, aluminum, carbon, a metal alloy, wood, Velcro, or a magnet.
In one embodiment, the support means 10 is between 8 to 15 cm thick. In one embodiment, the support means 10 is of varying thickness according to personal comfort. In one embodiment, the support means 10 has overall dimensions of roughly 15 to 40 cm tall and 15 to 30 cm wide. In one embodiment, the corners of the support means are beveled to avoid snagging and personal injury. In one embodiment, the corners of the support means are rounded to avoid snagging and personal injury.
In one embodiment, the quarter-wheel 12 is ovular. In one embodiment, the quarter-wheel 12 is 35 to 60 cm in width, measured along the base of the quarter-wheel. In one embodiment, the quarter-wheel 12 is with a 30 to 40 cm width, measured from the apex of the quarter-wheel to the axis of rotation.